'One of the problems with Alcoota is that we've never been able to date it directly,' Prideaux said.

'These Zygomaturus gilli specimens give us a strong tie in with similar specimens found at a site to the south of Melbourne that have been dated at about five-and-a-half million years. It is going to help us lock Alcoota in to a tighter timeframe,' he said.

The discovery gave an insight into 'how much there is to learn just at the one site, let alone the whole of Australia,' Prideaux said.

'The reality is we know perhaps one percent of Australia's fossil history. It's like having 10 pieces in a 1,000-piece jigsaw; there's a great temptation to reconstruct the picture based on those pieces, but the likelihood is that we'll almost certainly get it wrong.'